When saving ounces is essential, Criterion-manufactured Government contour barrels provide the perfect fit. With an overall weight as low as 1.70 pounds for the 16″ model, our Ultralight Government contour barrels offer an reasonably lightweight configuration allowing for rapid acquisition and maximized mobility. Uniformity of the bore dimension, groove dimension, twist rate, and a hand lapped finish prove to be necessary in enhancing the ultimate accuracy of each match quality barrel. These barrels feature a .223 Wylde chamber designed to accept both .223 Remington and 5.56 NATO ammunition. Also included is an M4 barrel extension. Chambers are finished, but barrels should be headspaced and installed by a qualified gunsmith.